Bronx Cheer

noun:
1. A rude sound indicating disapproval, made by sticking the tongue partly
out between the lips and blowing air out in a simulation of flatulence.
2. Any expression of derision or contempt.

[Probably after the Bronx, a borough of New York City, the home of Yankee
Stadium, where Yankees fans often expressed their opinion of the umpire's
decision or an unfavorable play that way.]

Bronx cheer has a rather unusual synonym: raspberry (also razzberry, often
shortened to razz). How in the world could a sound like that come to be
known as a raspberry? To learn this we take a peek at the fascinating
working of rhyming slang. "Raspberry tart" was used as a code for "fart"
and then the rhyming part was dropped. Other examples of rhyming slang are
"butchers" for "look", as in "Take a butchers at this!" (from butcher's
hook); "apples" for "stairs" (from apples and pears); china for mate (from
china plate).

Best-known rhyming slang was used by generations of London Cockneys, but
similar rhyming slang is found in many other parts of the world.

Some believe the reference to raspberry is from the appearance of the
tongue while "cheering".

"It wasn't a unanimous Bronx cheer. Many fans stood and applauded for
Martinez. Years of excellence outweigh one bad game. Still, it was an
out-of-body experience to hear any boos for Pedro on Opening Night at
Fenway Park."
Dan Shaughnessy; Voices of Fans Are Heard; Boston Globe; Apr 13, 2003.

X-Bonus

In this age, the mere example of nonconformity, the mere refusal to bend
the knee to custom, is itself a service. -John Stuart Mill, philosopher and
economist (1806-1873)